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refreshing 93 m5 suspension bushings

4K views 17 replies 8 participants last post by  alpinerunner 
#1 ·
Im looking to buy new front and rear suspension components today. I picked up a 93 M5 about 2 weeks ago with 180k on the clock. Suspension is tired. I was looking at some kits that FCP offers, but wanted to see how many of you recommend the sealed spherical bearing control arms before I buy standard HD stuff. Concerning the rear, I hear that the rear subframe bushings are usually worn by this mileage, and the diff mount. Anything else in the rear I should buy?
 
#2 ·
R trailing arm bushings, pitman arms (dogbones), easy to check if worn out.... I just replaced everything you mentioned plus all these. All the rubber is probably dead unless it has already been done...at least once. Check flex disc also while replacing rubber pieces. ( and engine mounts, transmission mounts, swaybar links, etc, etc...)
 
#5 ·
I'm hearing this terminology on my PO's paperwork and I'm confused. What do the rear pitman arms refer to? AFAIK there is just a rear trailing arm for rear suspension in the e34. What am I missing?
I also didn't know Powerflex made a rear subframe bushing. I may go that route.
 
#7 ·
Cool thanks. Just did some searching and I see the part now. I wasn't aware of any other parts back there besides the trailing arms themselves. It does indeed look like a dog bone! Do you know what it does? Can't tell from the diagram.
 
#8 · (Edited)
The rear dogbones are there to help control the rear toe geometry as the rear suspension compresses under cornering loads.
From experience, make sure to get the Lemforder dogbones. I've purchased other branded dogbones and they tend to squeak after putting on some mileage. Drove me nuts whenever I would go over speed bumps.

Here they are installed:





I'd also recommend getting the Moosehead spherical bearings as well as the E31 spherical bearing lower control arms as well. It's a little more pricier, but it'll last a long time with proper maintenance (Mooseheads) and will really tighten up the front end.

Mooseheads installed:


Good luck!
 
#9 ·
I also ordered the Mooseheads as my car seems to have a unique means for eating up the stock bushes.

I used Powerflex black for about 2 years....even became a dealer here !......but they just didn't seem to last long, most especially the post fire batches.

My Mooseheads arrived last week....once i install them i'll post up my findings. Suspensions have an extremely tough life here and if they're good here they'll work anywhere on the globe !!
 
#13 ·
I have yet to find an E34 M5 owner whose OEM RTA bearings wore out, by the way. I'm sure it's happened, but every time I've heard of someone removing them (big PITA), the bearings seemed perfect. Pretty good choice by BMW there, I think.

I also ordered the Mooseheads as my car seems to have a unique means for eating up the stock bushes.
That's not unique, believe me. At least poly bushings are easy to replace there, but the Mooseheads are serviceable, even better!

what does upgrading to e31 control arms do for handling? Is it a significant difference?
I installed E31 arms separately from Mooseheads, and the bearing in the E31 LCA absolutely made a more noticeable difference in tightening the steering response compared to the bearing in the UCAs. Bonus is that they're aluminum like stock E34 M5 arms, so they keep the unsprung weight equal.
 
#14 ·
Awesome, So Ill get the e31 LCA's and the moose head bushings are for the UCA's... Im trying to tighten up the steering as much as possible, as its the only part about the car that Im not crazy about..
The suspension modds I have are as follows, leveling delete w/ H+R springs/bilsteins, power flex urethane subframe bushes, and Racing dynamic strut bar...
What are some other suspension upgrades should I consider? Sway bars?
What I really need to figure out is whats causing play in the steering wheel and get an updated steering wheel..
 
#15 ·
On steering: (particularly if your box has 181k miles), you can try tightening the steering box adjustment, though at a certain point of wear in the box internals, that doesn't do much. Best case Ontario, you can remove play that way. Nothing fixes it like a new(er) box. Also consider replacing all of the steering links (apologies if you already did that, just reminding you), that removed some play in my case.

You've got most of the suspension covered, IMHO. I bought my '91 with a 100% shot suspension, so I've been through this. I did all of the steering links and arms, swaybar bushes and links, the E31 lowers, new Lemforder uppers (bought sans bushing, make sure you get those or you'll be pressing out a new bushing), and Mooseheads up front. A big difference for me in sound (in terms of clanks) and tightness was getting all 97 of those worn ball joints up front (ok, not really, but there are a LOT) replaced with fresh ball joints. I'm referring to the assort joints in all of those arms mentioned.

The rear is quite simple, I like the poly subframe bushings you already have; new dog bones, and swaybar bushes and links. As I mentioned in an earlier post, I'll bet your RTA bearings are still fine. Maybe add differential bushings to the rear and you're basically solid.

I could go on a diatribe about Bilstein being a poor match for this car, especially compared to Konis, but they'll do.

For "upgrades", you've basically just got bigger sways, and coil-overs. Since you have an M5, it's really only worth it to go aftermarket on swaybars as you have large factory bars already, and some would doubt the effectiveness of adding, say, the Nurburgring package Touring rear bar. Coil overs are a whole 'nother bag.

A cool addition, especially combined with your RD strut brace, is the E31 underbody x-brace. My touring has this (but not strut brace), but it came installed and I can't comment on what it actually changes--but it HAS to increase rigidity, one would think.
 
#16 ·
Thanks for the great info..
My suspension was 100% shot as well
Ill try that steering box adjustment and if that doesn't work, I'll get a new box.. Im not sure if I've replaced the smaller steering parts.. When I got the car 4 years ago I replaced most of the front suspension parts with a kit from somewhere, can't remember if the steering bits were a part of it.. Ill get those with the steering box..

I think I would rather have the konis too, I have some in my wrx and love them.. Eventually Ill get some in the m5..

I still need to get the power flex sway bar bushes and links,

Are the Racing Dynamic sway bars a huge improvement? They are only 2mm thicker than the stock bars, will that make a difference worth $500?
Or will I be fine just replacing the bushings on the stock bars with urethane and call it good..
 
#17 · (Edited)
On it's own, 2mm isn't a huge difference for a sway bar diameter (though, you may notice even that), but most aftermarket bars are also adjustable, meaning you can mount them in two or three different sets of holes of varying, multiplying stiffness. So they may only be 2mm "bigger", but can be set-up many times stiffer than stock. For a street cruiser I wouldn't, for a weekender/auto-x car, sure.
 
#18 ·
I'm with Bleedsblue to take a hard look at your steering box. Mine was shot at 130k miles and had significant on center play. It could feel like work steering components (tie rods, etc) but the on center play was truck like, and would tighten up after the suspension was loaded. Under the car, it can be confirmed by the input arm moving without the output arm moving on the steering box. I sent it out to https://benchworksteering.com/ who can rebuild it for around $450. They have no cores though so you car will be down for 1-2 weeks. There is a company on eBay with available cores to swap but they charge $850 for a rebuild.
 
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